Electrospraying employs electrostatic repulsion and acceleration resulting from a high voltage to create an aerosol or plume of droplets. Typically, the droplets will be a volatile solvent in which a molecule, ion or particle of interest is suspended or dissolved.
Evaporation of the solvent from the drop surface causes the space charge effects on an ever-decreasing droplet to make the droplet unstable, disintegrating into smaller, highly charged droplets, which can disintegrate entirely due to the high charge concentration.
A typical electrospray system will comprise, at its most basic:                a liquid supply source,        a capillary, needle, nozzle, or other delivery orifice leading from the liquid supply source,        a high voltage electrical source for applying a strong electric field to the liquid emerging from the open end of the delivery tube, and        a counter-electrode, which may be any surface to which the droplets are attracted (thus while the counter-electrode forms part of the electrospray system, it is often not an explicit part of the apparatus, since it may be an external surface towards which the nozzle approaches).        
Electrospraying finds applications in various fields, including thin film deposition processes, coating and painting processes, and mass spectroscopy. U.S. Pat. No. 6,764,720 discloses the use of electrospraying techniques for delivering drug particles into cells.
A consistent problem with electrospraying techniques is the reliable creation of an electrospray. The creation of a plume which will form an electrospray tends to be a matter of trial and error. This limits the use of the electrospray technique in any application where the liquid to be sprayed may frequently vary, since a change in the liquid properties (e.g. conductivity or viscosity) will generally mean that the parameters used to create an electrospray (source to target potential difference, liquid flow rate, nozzle dimensions) must also be varied.
The result is that one cannot easily pump a wide range of liquids through an electrospray apparatus and expect a reliable electrospray creation, since various parameters, equipment settings and even nozzles may need to be changed in order for a plume to result and an electrospray be formed.